[time-nuts] SLIP vs Ethernet for NTP
magnus at rubidium.dyndns.org
Mon Oct 24 04:26:49 UTC 2011
On 10/24/2011 05:14 AM, Doug Calvert wrote:
> On 10/23/2011 08:37 AM, Tijd Dingen wrote:
>> I seriously doubt that piping it through slip is going to help. You
>> still get to deal with slip + tcp protocol stack. I would expect gbit
>> ethernet with possibly some fifo/buffering setting adjusted gets you
>> better performance that RS232 (with or without slip). Just assemble
>> some raw frames on the source side and go.
> I think gig ethernet has a higher delay for smaller packets (ntp's udp
> datagram is tiny) than 100mbit ethernet.
There is very little to support this claim. The line-encoding could
possibly cause a small difference, but other than that I suspect
implementation issues rather than protocol by itself.
Even if you said that gigabit ethernet cards tend to have a higher delay
for smaller packets I would react, but then not on the technical aspect
but rather that I would like to see some statistics supporting the claim.
Only real technical issue is that datagram size needs to be 64 bytes and
that the header, trailer and inter-packet gap has the same size, but
behaves like larger relative parts than for larger packets. However,
this effect would be valid for fast ethernet too.
More information about the time-nuts